JP2007013594A - Manufacturing method of piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device adopting a manufacturing method of a piezoelectric device whereby sealing of each substrate part of a master substrate can surely be attained and the productivity is enhanced among manufacturing methods of piezoelectric devices. <P>SOLUTION: The manufacturing method includes: a step A of forming a conductor pattern 4 to the master substrate 9 comprising a plurality of substrate parts 1 arranged in a matrix form and sacrificial margins S provided among the substrate parts 1; a step B of mounting a piezoelectric resonator element 5 to the front principal side of each substrate part 1 of the master substrate 9; a step C of placing a master cover 11 with a sealing member 6 onto the master substrate 9; a step D of heating the master cover 11 while making a heater electrode 13 contact with the master cover 11 to melt the sealing member 6 by the heat of the heater electrode 13 thereby joining the master substrate 9 with the master cover 11; and a step E of slitting the master substrate 9 along the outer circumference of each substrate part 1 to obtain the piezoelectric devices 100. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric device such as a piezoelectric vibrator or a piezoelectric oscillator used in an electronic apparatus.

Conventionally, piezoelectric devices are used to generate reference signals for electronic equipment.
As such a conventional piezoelectric device, a seal ring is attached on a substrate made of a ceramic material or the like, and a quartz crystal vibration element as a piezoelectric vibration element is disposed on one end side of the upper surface of the substrate located inside the seal ring. A sealing structure is known in which a quartz vibrating element is hermetically sealed by mounting and fixing a metal cover on the seal ring (see, for example, Patent Documents). 1).

In addition, in this sealing structure, the piezoelectric vibration element accommodated in the substrate is not subjected to excessive heat that changes its characteristics, and is sealed by seam welding as a structure that can sufficiently withstand reflow solder during surface mounting. Stop structure.
In conventional seam welding, tungsten or molybdenum is used as a base layer around the opening of a box-shaped substrate having an opening on one side, and a sealing conductor film such as a Ni plating coating film is formed on the base layer. A seal ring such as 42 alloy or kovar is joined on the film by silver brazing or the like. After that, a rectangular cover made of the same metal material as the seal ring is placed on the opening of the substrate and temporarily attached, and then the roller electrode is pressed from the cover side to the four sides where the seal ring and the rectangular cover are joined. However, welding is performed by applying a large current between the cover and the seal ring by rotating the roller electrode while energizing the roller electrode (see, for example, Patent Document 2).

In addition, as a sealing method, there is a method of joining with a gold tin (Au—Sn) brazing material, and a method of heating in a vacuum atmosphere while being stored in a carbon jig is known.
JP 2002-111435 A (page 5-6, FIG. 2) Japanese Patent Laid-Open No. 2000-22013 (page 7, figure 3)

However, since seam welding, which is a conventional sealing method, requires a welding area of a certain size or more, when miniaturizing a crystal resonator element, characteristics such as crystal impedance (CI) value deteriorate, and the substrate is reduced. Since the welding area cannot be sufficiently taken when the size is reduced, the hermetic sealability cannot be maintained, so that neither the quartz resonator element nor the substrate can be further reduced in size.
In addition, it takes a long time to seal, and there are disadvantages that it cannot be produced on a master substrate.

Moreover, in the method of sealing with gold tin (Au—Sn) or the like using a conventional carbon jig, a process of changing from a carrier jig to a carbon jig is required when the method is carried out individually. For this reason, there is a drawback that productivity is lowered.
In addition, since the carbon jig is used, it is inevitable that dust is separated from the carbon jig and enters the accommodation space. In addition, there is a drawback that dust such as dust once entering the accommodation space cannot be easily removed.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems and provide a method for manufacturing a piezoelectric device that can reliably perform the sealing of each substrate portion of a master substrate and improve the productivity. To do.

  In order to solve the above-mentioned problems, the present invention provides a process for forming a conductor pattern on a master substrate having a plurality of substrate portions arranged in a matrix and a discard portion provided between the substrate portions. A, Step B for mounting the piezoelectric vibration element on the front main surface of the substrate portion of the master substrate, Step C for placing a master cover having a sealing material on the master substrate, and a heater on the master cover side The master cover is heated while contacting the electrodes, the sealing material is melted by the heat, and the step D is performed to join the master substrate and the master cover, and the master substrate is cut along the outer periphery of each substrate portion. And a step E of obtaining a plurality of piezoelectric devices.

  Further, in the process C, instead of the master cover, instead of the master cover, an individual cover portion having a sealing material is placed on the master substrate, and in the process D, the master cover is replaced with the master cover. The cover electrode may be heated while contacting the heater electrode, the sealing material may be melted by the heat, and the master substrate and the cover portion may be joined.

  In the present invention, the heater electrode may be made of titanium, molybdenum, tungsten, or ceramics.

  In the present invention, preliminary heating at 80 ° C. to 150 ° C. may be applied to the master substrate by a heating jig that generates heat.

  In the present invention, the heater electrode may be heated by a light source of a halogen lamp or a xenon lamp.

  According to the present invention, the heater electrode is brought into contact with the master cover side to heat the master cover, the sealing material is melted by the heat, and the master substrate and the master cover are joined. Bonding (sealing) in a state where the cover is placed is possible, and productivity can be improved. Further, by bringing the heater electrode into contact with the master cover, heat can be applied collectively, and each cover portion of the master cover is equally heated, so that stable airtight sealing can be achieved. Furthermore, since there is no possibility of dust entering compared to the case where a carbon jig is used, stable oscillation output can be achieved.

  Further, since the heater electrode is made of titanium, molybdenum, tungsten, or ceramics, the resistance value is high and the heat generation is good, so that the temperature can be easily controlled. Further, even if the heater electrode contacts the cover portion of the master cover, stable airtight sealing can be performed without damaging the cover portion.

  Further, before joining the master substrate and the master cover, a preheating of 80 ° C. to 150 ° C. is applied to the master substrate by a heating jig so that the heater electrode comes into contact with the cover portion of the master cover. By minimizing the thermal effect on the master substrate, it is possible to prevent damage to the master substrate.

  In addition, since the heater electrode is heated by the light source of the halogen lamp or xenon lamp to the heater electrode, it is possible to quickly increase the temperature of the heater electrode and to achieve a stable heat generation state. .

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate.

(First embodiment)
FIG. 1 is an exploded perspective view illustrating an example of a state before separation. FIG. 2 is a perspective view showing an example of a state in which a master cover is placed on a master substrate on which a piezoelectric vibration element is mounted. FIG. 3 is a perspective view showing a state before the heater electrode is pressed against the master cover. FIG. 4 is a perspective view showing a state in which the joined master substrate and master cover are cut for each piezoelectric device. FIG. 5 is a cross-sectional view of the piezoelectric device.

As shown in FIG. 5, the piezoelectric device 100 according to the present invention mainly includes a substrate (hereinafter referred to as “substrate portion”) 1, a lid (hereinafter referred to as “cover portion”) 2, and a piezoelectric vibration element 5. It is configured.
Here, the piezoelectric device 100 of the present invention has a conductor pattern 4 on a master substrate 9 having a plurality of substrate portions 1 arranged in a matrix and a discarding portion S provided between the substrate portions 1. In a state where the piezoelectric vibration element 5 is mounted on the front main surface of the substrate portion 1 of the master substrate 4, the master cover 11 having the sealing material 6 is placed on the master substrate 9, The master cover 11 is heated while the heater electrode 13 is in contact with the master cover 11 side, the sealing material 6 is melted by the heat, and the master substrate 9 and the master cover 11 are joined. It is obtained by cutting the master cover 11 along the outer periphery of each substrate part 1.

  The substrate portion 1 is formed by laminating a plurality of insulating layers made of a ceramic material such as alumina ceramic or glass-ceramic. The substrate portion 1 is formed with a concave portion 7 having an edge with a predetermined width and recessed in a rectangular shape, and a conductor pattern 4 is formed on the edge with the predetermined width. A plurality of external terminals 3 (see FIG. 5) including an input terminal (not shown), an output terminal (not shown), and a ground terminal (not shown) are provided on the lower surface of the conductor pattern 4. The surplus portion S is also made of the same material as the substrate portion 1.

  When the substrate unit 1 is made of alumina ceramic, the substrate unit 1 is connected to the external terminals 3 and the surface of the ceramic green sheet obtained by adding and mixing a predetermined amount of organic solvent to a predetermined ceramic material powder. A conductor paste to be the pad P, the conductor pattern 4 or the like, and a conductor paste to be a via conductor in a through-hole previously punched by punching the ceramic green sheet or the like are applied by a conventionally known screen printing or the like. In addition, it is manufactured by laminating a plurality of sheets and press-molding them, followed by firing at a high temperature.

  Further, the substrate portion 1 plays a role of accommodating the piezoelectric vibration element 5 made of quartz inside the recess 7. A pair of connection pads P that are electrically connected to the vibration electrodes of the piezoelectric vibration element 5 are deposited and formed on the bottom surface of the recess 7.

The piezoelectric vibration element 5 is formed by attaching and forming a pair of vibration electrodes on both main surfaces of a crystal piece having a thickness of 30 μm to 160 μm cut along a predetermined crystal axis, and a variable voltage from the outside forms the pair of vibration electrodes. When it is applied to the quartz piece, the thickness-shear vibration is caused at a predetermined frequency.
Such a piezoelectric vibration element 5 electrically and mechanically connects the vibration electrode attached to both main surfaces thereof and the corresponding connection pad P on the bottom surface of the recess 7 through the conductive adhesive 8. As a result, it is mounted on the bottom surface of the concave portion of the substrate portion 1.

  As shown in FIG. 5, the pair of connection pads P are electrically connected to the vibration electrodes of the piezoelectric vibration element 5 via the conductive adhesive 8 on the upper surface side, and the wiring inside the substrate unit 1 on the lower surface side. It is electrically connected to an input / output terminal (input terminal / output terminal) (not shown) via a conductor (not shown), a via-hole conductor (not shown) or the like.

  The conductor pattern 4 is formed to have a thickness of 10 μm to 25 μm by sequentially depositing a nickel (Ni) layer and a gold (Au) layer on the surface of an underlayer made of tungsten (W), molybdenum (Mo), or the like. It is formed and extends not only to the edge of a predetermined width, but also to the inner wall surface of the recess 7 and the outer surface of the substrate part 1.

  The conductor pattern 4 is for bonding a cover portion 2 to be described later to the upper surface of the substrate portion 1 via a sealing material 6. As described above, the conductive pattern 4 has a structure in which the Ni layer and the Au layer are sequentially deposited on the surface of the base layer made of tungsten (W) or molybdenum (Mo), thereby sealing the conductive pattern 4. The wettability of the material 6 can be improved, and the reliability and productivity of the piezoelectric device 100 can be improved.

  A via conductor (not shown) provided in a via hole (not shown) penetrating in the thickness direction is embedded in the substrate portion 1. As a result, the conductor pattern 4 deposited on the upper surface of the substrate portion 1 is joined to the cover portion 2 via the sealing material 6, whereby the cover portion 2 is connected to the ground terminal on the lower surface of the substrate portion via the via conductor (see FIG. (Not shown) and electrically connected. In this way, by electrically connecting the cover portion 2 made of metal to the ground terminal, the cover portion 2 is held at the ground potential when the piezoelectric device 100 is used. The piezoelectric shielding element 5 can be better protected than the unnecessary electric action from the outside by the shielding action 2.

  When the piezoelectric device 100 is mounted on an external wiring board such as a mother board, the external terminal 3 including the ground terminal is interposed between the wiring of the external wiring board and a conductive adhesive material such as solder. Function as a terminal for electrical connection.

  Further, the cover portion 2 disposed on the substrate portion 1 is a metal plate made of 42 alloy or the like, and a nickel (Ni) layer is annularly deposited on the lower surface along the outer periphery, and this Ni layer is attached. It is attached to the upper surface of the substrate portion 1 by being bonded to the conductor pattern 4 on the upper surface of the substrate portion through the sealing material 6. As a result, the recess 7 is closed and the inside of the recess 7 of the piezoelectric vibration element 5 is hermetically sealed. At the same time, the cover portion 2 is electrically connected to the ground terminal on the lower surface of the substrate portion 1 through the via conductor described above.

  Next, a method for manufacturing a piezoelectric device according to the present invention will be described.

(Process A)
As shown in FIGS. 1 and 5, the master substrate 9 is formed by laminating two layers of rectangular plate-like substrates, and further arranging a number of rectangular substrates arranged in a matrix, that is, a matrix of m columns × n rows. A substrate having a concave portion 7 is laminated. In the master substrate 9, a substrate portion 1 is formed around the concave portions 7 arranged in a matrix, and a surplus portion S is formed between the substrate portions 1. A pair of connection pads P are formed on the bottom surface of the recess 7, and a conductor pattern 4 for bonding to the cover portion 2 is attached and formed on the edge of the upper surface of the substrate portion 1 and having a predetermined width. An external terminal 3 (see FIG. 5) such as an input / output terminal and a ground terminal is attached and formed on the lower surface side of the substrate portion 1.

(Process B)
The piezoelectric vibration element 5 is mounted on the connection pad P on the bottom surface of the recess 7 provided in each substrate portion 1 of the master substrate 9.
One piezoelectric vibration element 5 is mounted on the bottom surface of the recess 7 of each substrate portion 1 of the master substrate 9, and the vibration electrode of the piezoelectric vibration element 5 and the connection pad P on the upper surface of the master substrate 9 are electrically conductive adhesive 8 (see FIG. 5)) and is electrically and mechanically connected.

(Process C)
Next, as shown in FIG. 2, the conductor pattern 4 formed on the upper surface of the substrate portion 1 of the master substrate 9 on which the piezoelectric vibration element 5 is mounted has a plurality of cover portions 2 corresponding one-to-one. The metal master cover 11 is placed so that the piezoelectric vibration element 5 is sealed.
A nickel (Ni) layer is formed on the upper surface of the master cover 11, and a clad gold-tin (Au-Sn) layer as a sealing material is further formed on the upper surface of the nickel (Ni) layer. . The thickness of the clad gold-tin (Au—Sn) layer is 10 μm to 30 μm. For example, the component ratio is 80% gold and 20% tin. In addition, similar to the master substrate 9 described above, the master cover 11 is also provided with a predetermined separation portion S between the cover portions 2.

(Process D)
As shown in FIG. 3, in a state where the master cover 11 is placed on the master substrate 9, the master cover 11 is heated while the heater electrode 13 is in contact with the entire surface of the master cover 11, and the sealing material 6 is heated by the heat. The master substrate 9 and the master cover 11 are joined by melting.

Such a bonding apparatus using the heater electrode 13 is called a so-called “pulse heat apparatus”.
This pulse heat device is composed of a power source, a heater electrode 13 heated by a power source voltage, and a thermocouple attached to the heater electrode 13. Since the heater electrode 13 is made of a material having a high resistance value such as titanium, molybdenum, tungsten, or ceramics, the heat capacity is large.

The master substrate 9 is set in a pulse heating device, and in the pulse heating device, air is sucked out to be in a vacuum state, and a power supply voltage is applied to the heater electrode 13 to cause the heater electrode 13 to generate heat.
Here, after reaching the set temperature, the sealing material 6 interposed between the master cover 11 and the master substrate 9 is melted by pressing the heater electrode 13 against the master cover 11, and the master cover 11 and the master substrate 9 are melted. And are joined.
Further, when the heater electrode 13 is pressed against the master cover 11, an appropriate pressure can be applied to the upper surface of the master cover 11 by providing an elastic body 14 such as a spring on the heater electrode 13. It becomes. Thus, the master cover 11 can be pressed against the master substrate 9 with an appropriate pressure.

Further, in joining the master substrate 9 and the master cover 11, it is preferable to perform sealing while heating the master substrate 9 with a heating jig K at a temperature of 80 ° C. to 150 ° C.
This is because if the temperature of the master substrate 9 is 80 ° C. to 150 ° C., even if the heater electrode 13 contacts the cover portion 2 of the master cover 11, the thermal effect on the master substrate 9 can be minimized. It becomes possible to prevent the master substrate 9 from being damaged. Further, by applying preheating to the master substrate 9, gas generated from the sealing material 6 can be released to the outside, so that generation of voids that occur during bonding can be reduced.
Here, the bonding state is best when the temperature of the master substrate 9 is 85 ° C. to 120 ° C.

  If the temperature of the master substrate 9 is lower than 80 ° C., a good bonding state is not obtained, and if the temperature of the master substrate 9 is higher than 150 ° C., the piezoelectric vibration element 5 made of quartz is adversely affected.

  The heating jig K is heated by a heater (not shown), and heats the master substrate 9 in advance before heating the master cover 11 with a pulse heater device.

  As a method of heating the heater electrode 13, the heater electrode 13 may be heated by irradiating the heater electrode 13 with a light source such as a xenon lamp or a halogen lamp and heating the heater electrode 13.

  The xenon lamp is a bulb in which a cathode and an anode are arranged, and the position of the highest luminance of the light emitting part is condensed at the focal position of the condensing mirror and emitted from the emission end of the optical fiber to this focal position.

  Similarly, the halogen lamp is provided with a tungsten filament in a bulb and sealed with a halogen gas. When this tungsten filament is energized and heated, it reacts with the halogen gas to produce a tungsten-halogen compound. The tungsten-halogen compound is transported to the vicinity of the filament by convection in the bulb, decomposed into tungsten and a halogen gas at a high temperature, and tungsten is precipitated in the filament. It is what happens.

The light beam generated here is used to heat the heater electrode 13, the heated heater electrode 13 is brought into contact with the master cover 11 to melt the sealing material 6, and the master material is melted by the molten sealing material 6. The cover 11 can be bonded to the master substrate 9. That is, the substrate part 1 can be sealed. At this time, a plurality can be sealed simultaneously.
Also, it is not necessary to route the wiring for supplying the power supply voltage into the vacuum furnace by irradiating with a xenon lamp or a halogen lamp rather than heating the heater electrode 13 by applying the power supply voltage. Etc. can be carried out efficiently.

(Process E)
Then, as shown in FIG. 4, by cutting along the outer periphery of each substrate portion 1 of the master substrate 9 and the cover portion 2 of the master cover 11, each bonded substrate portion 1 and cover portion 2 is divided (cut). )
The master substrate 9 is cut by dicing using a dicer or the like, and the master substrate 9 is divided into individual substrate portions 1, whereby each piezoelectric device 100 can be obtained.

(Second embodiment)
Next, a method for manufacturing a piezoelectric device according to the second embodiment of the present invention will be described.
In the method for manufacturing a piezoelectric device according to the second embodiment of the present invention, in Step C, the separated cover portions are placed on the master substrate, and in Step D, the cover portions are individually joined to the master substrate. This is different from the first embodiment.

That is, the individual cover portions are provided with a sealing material, and are placed on and bonded to each substrate portion of the master substrate.
Therefore, the individual cover portions are placed and bonded one by one. The cover part and the substrate part are joined by repeating the process C and the process D.

In addition to this, by repeating step C, the individual cover portions are placed on all the substrate portions provided on the master substrate, and in step D, each cover portion and the substrate portion of the master substrate are placed. And may be joined.
Thus, even if it comprises the manufacturing method of the piezoelectric device which concerns on 2nd embodiment, there exists an effect similar to 1st embodiment.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  For example, a surface-mount type crystal oscillator using a crystal as a piezoelectric vibration element has been described as an example of a piezoelectric device. Instead, another piezoelectric vibration element such as a surface acoustic wave (SAW) filter is used as a piezoelectric vibration element. The present invention is also applicable to the case of using, and has the same effect as the present embodiment. In addition, a semiconductor element can be used instead of the piezoelectric vibration element.

  In the above-described embodiment, the sealing material 6 is formed on the cover portion 2 of the master cover 11, but it may be formed on the substrate portion 1 of the master substrate 9.

  Furthermore, the master substrate 9 may be divided into a plurality of areas, a plurality of substrate portions may be formed for each area, and the area may be hermetically sealed with a heater electrode.

It is a disassembled perspective view which shows an example of the state before dividing into pieces. It is a perspective view which shows an example of the state which mounted the master cover on the master board | substrate which mounted the piezoelectric vibration element. It is a perspective view which shows the state before pressing a heater electrode to a master cover. It is a perspective view which shows the state which cut | disconnected the joined master substrate and master cover for every piezoelectric device. It is sectional drawing of a piezoelectric device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Piezoelectric device 1 Substrate part 2 Cover part 3 External terminal 4 Conductor pattern 5 Piezoelectric vibration element 6 Sealing material 7 Recess 8 Conductive adhesive material 9 Master substrate 11 Master cover 13 Heater electrode 14 Elastic body S Replacement part K Heating jig

Claims (5)

Forming a conductor pattern on a master substrate having a plurality of substrate portions arranged in a matrix and a surplus portion provided between the substrate portions; and
Mounting the piezoelectric vibration element on the front main surface of the substrate portion of the master substrate; and
Step C for placing a master cover having a sealing material on the master substrate;
Heating the master cover while contacting a heater electrode on the master cover side, melting the sealing material by the heat, and joining the master substrate and the master cover;
A step E of cutting the master substrate along the outer periphery of each substrate portion to obtain a plurality of piezoelectric devices. In step C,
Instead of the master cover,
Place the separated cover part having a sealing material on the master substrate,
In step D,
Instead of the master cover,
Heating the cover part while bringing the heater electrode into contact with the cover part, melting the sealing material by the heat, and joining the master substrate and the cover part;
The method for manufacturing a piezoelectric device according to claim 1.   The method for manufacturing a piezoelectric device according to claim 1, wherein the heater electrode is made of titanium, molybdenum, tungsten, or ceramics.   4. The method for manufacturing a piezoelectric device according to claim 1, wherein preheating of 80 ° C. to 150 ° C. is applied to the master substrate by a heating jig that generates heat. 5.   5. The method of manufacturing a piezoelectric device according to claim 1, wherein the heater electrode is heated by a light source of a halogen lamp or a xenon lamp.

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